In general, a stereoscopic image (or a three-dimensional (3D) image) is realized by projecting different images to the two eyes of a user. For a stereoscopic image projected on a large-sized screen in a movie theater, mainly used is a polarization method in which a left image and a right image are transmitted through polarizing glasses that include left and right polarizing lenses having different polarizing directions which are perpendicular to each other. Images are captured using two cameras, the two captured images are converted using a polarizing means such that the polarizing directions of the images are perpendicular to each other, the images having polarizing directions perpendicular to each other are displayed on a screen, and a user views the images captured by the two cameras through his/her left and right eyes in the state in which the user wears the polarizing glasses, whereby a stereoscopic image is realized.
FIG. 1 is a view showing the structure of a conventional dual projector system for displaying a stereoscopic image.
In order to display a stereoscopic image using the polarization method as described above, the conventional dual projector system is configured such that one of the two-dimensional (2D) projectors 1 and 2 emits a left image and the other of the two-dimensional (2D) projectors 1 and 2 emits a right image. These images pass through polarizing filters 3 and 4, polarizing directions of which are perpendicular to each other, and are then projected on a screen 5. A viewer views the left image and the right image, which overlap each other on the screen 5, through a left image lens 7 and a right image lens 8 of polarizing glasses 6 in the state in which the viewer wears the polarizing glasses 6, whereby a depth effect is acquired.
In the above method, different polarizations may be applied to the left image and the right image, irrespective of whether the polarization is linear polarization or circular polarization.
The conventional dual projector type stereoscopic image display system has been replaced by a single projector system, which is configured such that a projector alternately emits a left image and a right image.
FIG. 2 is a view illustrating a circular polarizing filter type single projector system.
As shown in FIG. 2, the single projector type stereoscopic image display system includes a projector 201 for alternately emitting a left image and a right image, a circular polarizing filter unit 202 including a left image polarizing filter and a right image polarizing filter, and a filter driving unit 203 for rotating the circular polarizing filter unit 202 in synchronization with the emission of the left image and the emission of the right image by the projector 201. In addition, as shown in FIG. 2, the single projector system may further include a synchronization unit 204 for synchronizing the emission of the left image by the projector 201 with the emission of the right image by the projector 201 and transmitting the acquired synchronization information to the filter driving unit 203.
When stereoscopic image content, in which left images and right images are sequentially stored, is input to the projector 201, the projector 201 continuously emits the stereoscopic image content. As described above, the circular polarizing filter unit 202 includes the left image polarizing filter and the right image polarizing filter. The circular polarizing filter unit 202 is rotated such that the left image polarizing filter is located at an emission port of the projector 201 when each left image is emitted by the projector 201 and such that the right image polarizing filter is located at the emission port of the projector 201 when each right image is emitted by the projector 201.
In the single projector type stereoscopic image display system described above, however, brightness is greatly reduced because the image light emitted by a single projector is split into left and right images.